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Induction from coiled up leads???

01-14-2009, 11:08 PM

Over the years I have heard over and over about the affects of having your leads coiled up and it having adverse affects. I have spent the last few hours searching the net hoping to find some "GOOD" info on this.

A buddy of mine recently told me that the more you wrap your lead (don't recall which one) around something like a leg on a table, the more induction you get. His take on it was that in some cases this is a good thing and in some cases it is not.

To make a long story short, a guy I know that has welded on pipe for the last 30 years or so, ran a root pass with my Trailblazer 302 and said he didn't much like the way it ran. You could tell that he did a pretty good job but you could also tell that it really didn't want to tie in very well. I can't help but wonder if having 125' or so of lead wrapped up on a "steel wheel" might be having an affect on the arc?

Hello,ive got a pipepro and i can tell really tell the difference when my 100'ers are coiled up or strung out.before i built my reels i had my 100' leads coiled in a box built into the flatbed,i was welding and couldnt get my bead in at all,it was all over the place.As i walked by my rig i noticed all the metal filings clinging to the leads so i got em out,strung em out and the problem went away.....I now have my 100' on reels for long distance and 25'in the well for Right away work.

Comment

Induction happens with coiled conductors and "changing" current.
That's basic electricity. It's the same thing as what happens in
a transformer.

Note that I say "changing" current, not "alternating" current.
Even when the welder is set for DC, when the current starts
to flow (such as when you strike an arc or pull the MIG trigger)
there is a change in the current in the conductor and the
inductor, well, inducts... but it's transient and goes away
quickly. The same happens when you stop -- it's a change
in the current... Even with DC Stick, the current is varying
slightly as you weld, which causes the inductor to induct.
With MIG, the current is switching on/off fairly frequently,
so that too will cause the inductor to induct.

Whether that induction affects the welds or not, I can not say.
I imagine that it could. But I do not know.

Frank

Comment

? DC makes good electromagnets. You don't need to be inducing elec energy into other things or shifting the direction or amps to make a strong magnetic field with a large coil of wire. The magnetic field impinges on itself.

Comment

Even with the welding wrap coiled on the ground there is a magnetic air gap, though it's tough to get a tight coil when you plunk your cables on the ground but it's still there to some degree.

Say if you have a reels with a steel core, like the home mades, or even Shel-ryn, or Swishco you have a large magnetic inductance happening which effects circuit board operated machines depending on where your reels are located in position with those internal boards. Even in non circuit board machines, that magnetic inductance can cause arc blow.

True Aluminum reels with a Aluminum not steel core, act like a air gap where there is a diffused magnetic inductance, but not enough to effect much.

Comment

125' of cable wrapped in a 12" loop 6" wide (would be about 40 turns) is going to add 500 microhenries of inductance, or .0005H.

I doubt that will cause you problems. More inductace results in a more stable current. However, if this is located next to your welder, you could be putting a large magnetic field into it that will mess up the control circuitry.

If you wind it one way for half its length, then wind it the other way, the opposite magnetic fields will cancel each other out. Well, almost anyway, since I doubt they'd be EXACTLY equal and opposite.

80% of failures are from 20% of causesNever compromise your principles today in the name of furthering them in the future."All I ever wanted was an honest week's pay for an honest day's work." -Sgt. Bilko"We are generally better persuaded by reasons we discover ourselves than by those given to us by others." -Pascal"Since we cannot know all that there is to be known about anything, we ought to know a little about everything." -Pascal

Comment

Yes, coiled up cables will affect the welding arc. It depends what type of metal and quantity they are coiled around, how tight the coils are and how many turns there are. These factors determine the amount of inductance and will affect the responsiveness of the arc. While adding inductance may be good or bad for arc performance depending on what you are doing, it will hurt arc starts.
There is a lot of good feedback from the responses that pretty much say the same thing. Playing around with it is the best way to see what it does for you.

Comment

Do you think it would be worth the time to convert from a steel reel to an aluminum one?

Also, I currently keep my leads tied to each other for their full length of about 125' and have to disconnect my leads from the reel if I want to change length. I was thinking about making two aluminum reels facing each other and have them insulated from each other with pvc pipe (about 5" diameter) to wind the leads on and have the current run through the bearings on each one. This way the leads are always hot. Any problems with this idea?

Comment

It would not be worth the time because almost all of the inductance is caused by the wound up leads. The reel is negligible.

I wouldn't bother with it.

80% of failures are from 20% of causesNever compromise your principles today in the name of furthering them in the future."All I ever wanted was an honest week's pay for an honest day's work." -Sgt. Bilko"We are generally better persuaded by reasons we discover ourselves than by those given to us by others." -Pascal"Since we cannot know all that there is to be known about anything, we ought to know a little about everything." -Pascal